Physics
Physics
Problem
A student is investigating how the nature of the image produced by a thin convex lens changes as the object is moved to different positions along the principal axis. a. (i) Explain qualitatively how the position, size and nature of the image vary when the object is placed (a) beyond , (b) at , (c) between and , and (d) between the optical centre and of the lens. b. (ii) Draw a neat and properly labelled ray diagram for case (c) only. c. (iii) Give a reason why a real image formed by the convex lens can be obtained on a screen whereas a concave lens cannot project a sharp image on a screen for any position of the object.Intuitive explanation
The key insight is that a convex lens acts like a "position detector"—where you place the object determines everything about the image (size, orientation, and whether it's real or virtual). The critical distances are the focal length and the center of curvature : beyond gives a small real image, between and gives a large real image, and inside gives a virtual magnified image. By systematically moving the object and observing how the image changes, you'll see the lens equation play out in real space.
Intuitive explanation
The key insight is that a convex lens acts like a "position detector"—where you place the object determines everything about the image (size, orientation, and whether it's real or virtual). The critical distances are the focal length and the center of curvature : beyond gives a small real image, between and gives a large real image, and inside gives a virtual magnified image. By systematically moving the object and observing how the image changes, you'll see the lens equation play out in real space.